The onset of asthma is often during childhood;and when the child is atopic, the child is more likely to continue to have asthma as an adult. Diseases such as asthma have a higher prevalence in childhood;and management that alters the morbidity of allergic diseases in children may impact disease outcomes in future years. This study examines techniques for the detection of inflammation in children with respiratory diseases due to allergy or immunologic dysfunction. Emphasis is on non-invasive methods. We will use information gathered to determine if there are inflammatory markers that may be diagnostic or representative of disease severity, and thus useful in management. Preliminary data supports the concept of ongoing airway inflammation in asymptomatic children with asthma. It also supports the existing use of nitric oxide as a marker of airway inflammation that may or may not correlate with bronchoconstriction as demonstrated by spiromertry. Furthermore, an elevated expired nitric oxide level seen in association with airway inflammation may be associated with a decrease in airway pH, previously documented during an asthma exacerbation. A similar pattern was not demonstrated in healthy matched controls. Of interest, we completed the analysis of cytokine data using EBC samples for all of the first visits and demonstrated significant differences in several inflammatory cytokines in patients with asthma as compared to healthy controls. We have completed the data collection in this longitudinal study of non-invasive measurements of airway inflammation in children with asthma and healthy-matched controls and we are preparing the manuscript for publication. We have also enrolled 25 of the target 30 children with immunodeficiencies and recurrent respiratory diseases for a comparison of airway inflammatory markers of infection with those associated with allergic airway inflammation.